Low RPMS
 

I have a 1991 hatch with a B16A2 in it. from about900rpms tillEXACTLY 4000rpms, the car lags. once it hits 4 grand, it rips, and i mean its not a small difference but a really large one. I believe the vtec kicks in at 4000rpms but it shouldn't make THAT much of a difference should it? any ideas one getting more power in really low rpms?

Thanks a lot.